J. Huang, Z. Zhuang, J. Li, und C. Giles. Proceedings of the 2008 International Conference on Web Search and Data Mining, Seite 107--116. New York, NY, USA, ACM, (2008)
Q. He, B. Chen, J. Pei, B. Qiu, P. Mitra, und L. Giles. Proceedings of the 18th ACM conference on Information and knowledge management, Seite 957--966. New York, NY, USA, ACM, (2009)